In Predict, you may exclude variables in the Load Options when first loading a dataset, but if you did not do that there are a couple of other options. In the Statistics tab (the landing page when you first load an analysis) you can right-click on any variable and choose Hide Selected Columns. This will remove the variable from reference in every analysis window.
If you prefer to be able to keep the variable in the analysis, but just exclude it from the model – in the Model tab and then in the Automine tab you can right-click on the variable(s) and select Exclude Variables and their transforms from modeling
